Affiliations: Research Center for Eco-Environmental Sciences,
Chinese Academy of Sciences, Beijing 100085, China | Institute of Geophysical and Geochemical Exploration,
Langfang 065000, China
Abstract: Thirty-nine deep subsurface soils (150–180 Gm depth) near the
outskirts of Beijing were investagated. The concentrations including n-alkanes
from C_{13} to C_{36}, pristane and
phytane were in the range of 0.60 to 170.10 μg/g, with a median value of
4.26. Carbon preference index values for n-alkanes ranged from 1.08 to 2.98,
with a median value of 1.48. The percentage contribution of "wax" n-alkanes
was in the range of 6.03%–46.22%. A predominance of odd/even carbon
n-alkanes and unresolved complex mixtures with different shapes and ranges were
frequently observed. Factor analysis reduced the data set into three principal
components and confirming contributions from Iow (19.58%), medium (20.49%)
molecular weight species and long-chain n-alkanes (43.41%), respectively.
Molecular biomarkers such as pristane, phytane, hopanes and steranes were
detected. Based on the principal component analysis, the concentration profiles
and molecular markers, it was found that the aliphatic hydrocarbons were from
both biogenic and anthropogenic sources.
Keywords: deep subsurface soil, n-alkanes, spatial distribution, molecular markers, diagnostic indices
